> From: Dexuan Cui
> Sent: Thursday, March 21, 2019 7:09 PM
 
> IMO there are 2 issues in ndctl/monitor.c: filter_dimm():
> 
> 1. IMO the cmd numbers ND_CMD_SMART (1) and
> ND_CMD_SMART_THRESHOLD(2) are not really device-neutral. They
> work for ndctl/lib/intel.c and it looks they happen to work for
> ndctl/lib/hpe1.c, as hpe "happens" to have:
>        NDN_HPE1_CMD_SMART = 1,
>        NDN_HPE1_CMD_SMART_THRESHOLD = 2,
> 
> But for ndctl/lib/msft.c, 1 and 2 mean different things. See [1].
> So the current "ndctl monitor" can't support msft.c.
> 
> For ndctl/lib/hyperv.c, 1 and 2 means:
>         ND_HYPERV_CMD_GET_HEALTH_INFO = 1,
>         ND_HYPERV_CMD_GET_SHUTDOWN_INFO = 2,
> They're also incompatible with ND_CMD_SMART and
> ND_CMD_SMART_THRESHOLD.
> Of source, the current code can "work" since these ND_HYPERV_CMD*
> numbers happen to be the same as ND_CMD_SMART and
> ND_CMD_SMART_THRESHOLD. So this may not be an isue for hyperv.c.

Actually, this _is_ an issue for NVDIMM_FAMILY_HYPERV (and the other
families except for NVDIMM_FAMILY_INTEL) : see the kernel function
acpi_nfit_register_dimms(), where ND_CMD_SMART is set in the 
"cmd_mask" only for NVDIMM_FAMILY_INTEL.

So, on Hyper-V, ndctl_dimm_is_cmd_supported(dimm, ND_CMD_SMART) 
is always false, and "ndctl monitor" exits with "no smart support".
 
> 2. The current code assumes ND_SMART_ALARM_VALID must be supported.
> However, NVDIMM_FAMILY_HYPERV doesn't support it, so currently
> ndctl/monitor.c: filter_dimm() reports an error and returns -- for Hyper-V,
> we should not return... hence I made this patch.
> 
> Of source, we can add a new op to dimm->ops, e.g.
> ops->monitor_supported() and then change the common code accordingly,
> but I can imagine that would require a lot more changes and I guess it may not
> worth that effort? Please share your insights!

Looking forward to your suggestion!
 
Thanks,
-- Dexuan

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